Dear Aspirant,

The details collected by the exam authority is only for the communication and verification befor the exam is conducted. After the exams and results announcement, the data that you have given them does not really affect you or your life in any way.

College applications have their own format and details to be filled. They don't rely on the details you have in the exam application ( except for important details like your caste, scores etc)

Hence, unless there is a really bad emergency (highly unlikely event) there is no reason for your phone number in the exam application form to affect your college life.

It is insanely difficult to trace all the data as they have a garagntuan amount of information at their disposal.

Hope this helps.